2,045 research outputs found

    Predicting the minimum liquid surface tension activity of pseudomonads expressing biosurfactants

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    Bacteria produce a variety of biosurfactants capable of significantly reducing liquid (aqueous) surface tension (γ) with a range of biological roles and biotechnological uses. In order to determine the lowest achievable surface tension (γMin), we tested a diverse collection of Pseudomonas-like isolates from contaminated soil and activated sludge, and identified those expressing biosurfactants by drop-collapse assay. Liquid surface tension reducing ability was quantitatively determined by tensiometry, with 57 isolates found to significantly lower culture supernatant surface tensions to 24.5 – 49.1 mN m−1. Differences in biosurfactant behaviour determined by foaming, emulsion and oil-displacement assays, was also observed amongst isolates producing surface tensions of 25 – 27 mN m−1, suggesting that a range of structurally-diverse biosurfactants were being expressed. Individual distribution identification (IDI) analysis was used to identify the theoretical probability distribution that best fitted the surface tension data, which predicted a γMin of 24.24 mN m−1. This was in agreement with predictions based on earlier work of published mixed–bacterial spp. data, suggesting a fundamental limit to the ability of bacterial biosurfactants to reduce surface tensions in aqueous systems. This implies a biological restriction on the synthesis and export of these agents or a physical-chemical restriction on their functioning once produced

    Water Uptake Threshold of Rabbiteye (\u3ci\u3eVaccinium ashei\u3c/i\u3e) Blueberries and Its Influence on Fruit Splitting

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    Split-resistant and split-susceptible rabbiteye blueberry fruit were evaluated at all stages of development to determine \u27\u27water uptake thresholds\u27\u27 by soaking in distilled water. Weight increase after soaking was measured, and percent weight gain was calculated to take into consideration the weight increase of the fruit from development. The ratio of percent increase in volume to weight increase resulting from water uptake was calculated. Ratios of percent water uptake to weight increase between splitsusceptible \u27Tifblue\u27 and split-resistant \u27Premier\u27 blueberries were found to be similar. The split-susceptible \u27Tifblue\u27 had a 1.6 g/50 fruit increase with a 1.7% water uptake and a ratio of 1.08. \u27Premier\u27 had a higher weight increase with 3.3 g/50 fruit and also a higher percentage of water uptake at 3.6% providing a ratio of 1.09. Although both absorbed water at a constant rate shown by a linear increase of weight increase over time, \u27Premier\u27 absorbed a significantly greater amount of water than did \u27Tifblue\u27 yet remained intact and did not split

    Priming winter wheat seeds with the bacterial quorum sensing signal N-hexanoyl-L-homoserine lactone (C6-HSL) shows potential to improve plant growth and seed yield

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    Several model plants are known to respond to bacterial quorum sensing molecules with altered root growth and gene expression patterns and induced resistance to plant pathogens. These compounds may represent novel elicitors that could be applied as seed primers to enhance cereal crop resistance to pathogens and abiotic stress and to improve yields. We investigated whether the acyl-homoserine lactone N-hexanoyl-L-homoserine lactone (C6-HSL) impacted winter wheat (Triticum aestivum L.) seed germination, plant development and productivity, using two Ukrainian varieties, Volodarka and Yatran 60, in both in vitro experiments and field trials. In vitro germination experiments indicated that C6-HSL seed priming had a small but significant positive impact on germination levels (1.2x increase, p < 0.0001), coleoptile and radicle development (1.4x increase, p < 0.0001). Field trials over two growing seasons (2015-16 and 2016-17) also demonstrated significant improvements in biomass at the tillering stage (1.4x increase, p < 0.0001), and crop structure and productivity at maturity including grain yield (1.4 – 1.5x increase, p < 0.0007) and quality (1.3x increase in good grain, p < 0.0001). In some cases variety effects were observed (p ≤ 0.05) suggesting that the effect of C6-HSL seed priming might depend on plant genetics, and some benefits of priming were also evident in F1 plants grown from seeds collected the previous season (p ≤ 0.05). These field-scale findings suggest that bacterial acyl-homoserine lactones such as C6-HSL could be used to improve cereal crop growth and yield and reduce reliance on fungicides and fertilisers to combat pathogens and stress

    Potential role of predators on carbon dynamics of marine ecosystems as assessed by a Bayesian belief network.

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    While the effects of climate change on top predators are well documented, the role of predation on ecosystem level carbon production is poorly developed, despite it being a logical consequence of trophic dynamics. Trophic cascade effects have shown predator mediated changes in primary production, but we predict that predators should lower the overall biomass capacity of any system with top down control. Through a simple Bayesian belief network model of a typical marine foodweb, we show that predator removal, as is common through activities such as fishing and shark finning, results in higher biomasses of lower trophic level fish and zooplankton, resulting in higher net carbon production by the system. In situations common throughout much of the ocean, where activities such as shark finning and over fishing reduce the highest tropic levels, the probability of net carbon production increasing in the model was ~ 60%, and unlike previous studies on simple food chains, trophic cascade effects were not present. While the results are preliminary, and sources of uncertainty in data and models are acknowledged, such results provide even more strength to the argument to protect open sea fish stocks, and particularly large predators such as sharks, cetaceans and game fish

    Laboratory Method to Estimate Rain-Induced Splitting in Cultivated Blueberries

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    Preharvest rainfall that occurs when fruit are fully ripe or approaching full ripeness can result in detrimental fruit splitting in rabbiteye and southern highbush blueberries. This study was initiated to develop a laboratory method to model rain-related incidence of splitting in cultivated blueberries with the goal of predicting the incidence of splitting in blueberry cultivars and selections. Multiyear field surveys of rabbiteye and southern highbush cultivars show that the incidence of rain-related splitting is strongly cultivar-dependent. Laboratory values for forced splitting and naturally occurring rain-related field splitting data show a strong correlation indicating that the incidence of fruit splitting can be accurately estimated by this laboratory method. Soaking the berries in distilled water 14 h at room temperature gives a confident determination of splitting tendencies. Blueberry breeders and geneticists can use this method to evaluate new potential blueberry cultivars for splitting tendencies as part of routine screening. This would lead to a long-term goal of reducing splitting susceptible blueberry cultivars in commercial plantings

    Апеляційний перегляд постанов місцевого суду, винесених за розглядом скарг на постанову про порушення кримінальної справи

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    Досліджуються основні проблеми апеляційної перевірки правомірності порушення кримінальної справи.Исследованы основные проблемы апелляционной проверки правомерности возбуж­дения уголовного дела.The article is dedicated to the main problems of the appellate review of instituting pros­ecution

    Study of diffusion weighted MRI as a predictive biomarker of response during radiotherapy for high and intermediate risk squamous cell cancer of the oropharynx: The MeRInO study

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    Introduction and background: A significant proportion of patients with intermediate and high risk squamous cell cancer of the oropharynx (OPSCC) continue to relapse locally despite radical chemoradiotherapy (CRT). The toxicity of the current combination of intensified dose per fraction radiotherapy and platinum based chemotherapy limits further uniform intensification. If a predictive biomarker for outcomes from CRT can be identified during treatment then individualised and adaptive treatment strategies may be employed. Methods/design: The MeRInO study is a prospective observational imaging study of patients with intermediate and high risk, locally advanced OPSCC receiving radical RT or concurrent CRT Patients undergo diffusion weighted MRI prior to treatment (MRI_1) and during the third week of RT (MRI_2). Apparent diffusion coefficient (ADC) measurements will be made on each scan for previously specified target lesions (primary and lymph nodes) and change in ADC calculated. Patients will be followed up and disease status for each target lesion noted. The primary aim of the MeRInO study is to determine the threshold change in ADC from baseline to week 3 of RT that may identify the sub-group of non-responders during treatment. Discussion: The use of DW-MRI as a predictive biomarker during RT for SCC H&N is in its infancy but studies to date have found that response to treatment may indeed be predicted by comparison of DW-MRI carried out before and during treatment. However, previous studies have included all sub-sites and biological sub-types. Establishing ADC thresholds that predict for local failure is an essential step towards using DW-MRI to improve the therapeutic ratio in treating SCC H&N. This would be done most robustly in a specific H&N sub-site and in sub-types with similar biological behaviour. The MeRInO study will help establish these thresholds in OPSCC

    A longitudinal interpretative phenomenological analysis of the process of kidney recipients’ resolution of complex ambiguities within relationships with their living donors

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    Much previous research into living kidney donation has focused on the decision making of the donor, despite evidence suggesting this may be a more psychologically challenging time for the recipient. This longitudinal study explores the experiences of four recipients of kidneys from living donors throughout the transplant process. Transcripts were analysed using Interpretative Phenomenological Analysis (IPA). Three themes arose from the data, which were: Changing perceptions of relationships with kidney donors; Upbeat, temporal strategies for remaining positive; and Journey of the self. Findings from the first theme are presented in detail here. It was found that each participants’ relationship with their donor grew and developed in different ways, presenting their own complex challenges in terms of developing relationships and ambiguity around the decision to use the chosen donor

    ‘Treading water but drowning slowly’: what are GPs’ experiences of living and working with mental illness and distress in England? A qualitative study

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    Objectives This paper provides an in-depth account of general practitioners’ (GPs) experiences of living and working with mental illness and distress, as part of a wider study reporting the barriers and facilitators to help-seeking for mental illness and burn-out, and sources of stress/distress for GP participants. Design Qualitative study using in-depth interviews with 47 GP participants. The interviews were audio recorded, transcribed, anonymised and imported into NVivo V.11 to facilitate data management. Data were analysed using a thematic analysis employing the constant comparative method. Setting England. Participants A purposive sample of GP participants who self-identified as: (1) currently living with mental distress, (2) returning to work following treatment, (3) off sick or retired early as a result of mental distress or (4) without experience of mental distress. Interviews were conducted face to face or over the telephone. Results The findings report GP participants’ in-depth experiences of distress and mental illness with many recollecting their distressing experiences and significant psychological and physical symptoms relating to chronic stress, anxiety, depression and/or burn-out, and a quarter articulating thoughts of suicide. Many talked about their shame, humiliation and embarrassment at their perceived inability to cope with the stresses of their job and/or their symptoms of mental illness. Conclusions These findings paint a concerning picture of the situation affecting primary care doctors, with participants’ accounts suggesting there is a considerable degree of mental ill health and reduced well-being among GPs. The solutions are complex and lie in prevention and provision. There needs to be greater recognition of the components and cumulative effect of occupational stressors for doctors, such as the increasing workload and the clinical and emotional demands of the job, as well as the need for a culture shift within medicine to more supportive and compassionate work environments
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